Defender Scott Laird was floored by the blow following the final whistle as the League Two side celebrated their 3-1 win over their Premier League opposition.

Stevenage manager Graham Westley confirmed that Laird had been poleaxed by the blow in an incident that marred the most glorious night in their history.

Westley said: "Scott Laird was stood celebrating with the fans and a fan just came over and smashed him from the side. He went to the ground and it is a shame for the afternoon to end in that way.

"He is a bit bewildered. He (the fan) gave him a right-hander, just smashed him across the cheek and knocked him to the ground.

"He said to me, 'It's lucky I've got a big head to take it.' It was a sad way for things to end."

A video of the incident was swiftly posted on the internet and the FA is certain to study the evidence next week.

An FA spokesman said: "It's something that should be flagged up in our meeting on Monday. It might be that there was a stadium advisor at the game who'll be able to advise us on that."

Westley, however, was more concerned in ensuring that his players got the credit for one of the great FA Cup performances.

He said: "It's not my business to deal with those matters. It's in other people's hands.

"Look, Mark Roberts had his nose busted in the first half. Footballers take bangs, they take knocks. You can't suggest that is the right way for a football match to end with those things going on but balls get thrown at people, players get kicked, tackles get made.

"We're not people who spend our lives griping about bangs and knocks. I don't think it's the way things should be conducted, but let's leave it at that.

"I wouldn't want it to take the gloss off the players because they have put in a fantastic shift and the focus should be on the performance they have put in."